Mobile radio frequency (RF) chip designs (e.g., mobile RF transceivers) have migrated to a deep sub-micron process node due to cost and power consumption considerations. The design complexity of mobile RF transceivers is further complicated by added circuit function to support communication enhancements. Further design challenges for mobile RF transceivers include analog/RF performance considerations, including mismatch, noise, and other performance considerations. The design of these mobile RF transceivers includes the use of a differential inductor, for example, in combination with capacitors to provide the resonant tank for a voltage controlled oscillator.
In order to achieve good phase noise performance (e.g., 1/f noise performance) in a voltage controlled oscillator (VCO), a differential and common mode inductance of an inductor (e.g., a differential inductor) should be precisely controlled. While the differential inductance of the inductor is generally well controlled because of a virtual ground, a common mode inductance of the inductor can be significantly affected by external parasitics from routing, packaging, etc., if a low impedance common mode alternating current (AC) ground is not properly provided.